High-Energy Li−S Batteries Achieved by Compact S Cathode and Polysulfide Adjoining Interface Engineering

Abstract

To maximize the energy density of Li−S batteries, it is crucial to increase the loading level of sulfur cathode and minimize the electrolyte content. However, excessive amounts of lithium polysulfides (LiPSs) generated in the high loading Li-S batteries limit the stable cycling. In this study, a high-loading S cathode with a three-dimensional (3D) network structure is fabricated using a simple pelletizing method, and the exhausting overcharging phenomenon, which occurs in the high loading Li−S cell, is successively prevented by pre-treating the lithium metal anode. Moreover, adding a diluent to the electrolyte containing viscous LiPSs enables the facile conversion between S species during the cycling of high-loading Li−S cells under lean electrolyte conditions. Finally, a prototype Li−S pouch cell with high energy density (427 Wh kg−1) was realized by combining a compacted 3D cathode with a high-loading, pretreated thin lithium metal and diluent-modified electrolyte. We believe that the results reported herein will be a good guideline to establish proper strategies to achieve high energy density Li−S batteries.